A seven-membered ring boron oxide compound, preparation method thereof, and electroluminescent device

Abstract

The present invention belongs to the field of organic light-emitting materials and semiconductor technology, and provides a seven-membered ring borane compound, a preparation method thereof, and an electroluminescent device. The structural formula of the seven-membered ring borane compound is shown in formula (1): [0001] An electroluminescent device prepared using the seven-membered ring borane compound as a guest luminescent material solves the technical problem of low luminescence efficiency of existing compounds containing borane structures as luminescent materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic luminescent materials and semiconductors, and particularly relates to a seven-membered ring boron-oxygen compound, a preparation method thereof, and an electroluminescent device. Background Art

[0002] In recent years, organic light emitting diodes (OLEDs) have become a hot research direction in the field of lighting and display due to their excellent properties such as self-luminescence, high brightness, high contrast, see-through, wearable, foldable, low energy consumption, wide viewing angle and low temperature resistance.

[0003] A typical OLED structure consists of an anode, a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and a cathode. When voltage is applied to the anode and cathode, holes injected from the anode move through the HTL to the EML, and electrons injected from the cathode move through the ETL to the EML. Electrons and holes recombine in the EML to produce excitons, which transfer energy to the luminescent material in the emission layer, causing the material to emit light.

[0004] In recent years, compounds containing boron-oxygen (BO) or boron-nitrogen (BN) structures have emerged as a new class of luminescent materials. The introduction of boron atoms imparts a rigid molecular framework and an alternating distribution of frontier orbitals, contributing to high-efficiency, narrow-bandwidth luminescence and significantly improving luminescent color purity.

[0005] Korean patent application publication number KR1020090008736A discloses azaboranthrenone or xanthone derivatives and organic electronic devices using the same. Such compounds can be used in the light-emitting layer, electron transport layer and / or electron injection layer, hole transport layer and / or hole injection layer, and hole blocking layer of OLED devices. In 2016, Tetrahedron (Volume 72, Issue 11, 17 March 2016, Pages 1477-1484) reported an article entitled "10,9-Oxaboraphenanthrenes as luminescent fluorophores", which disclosed compounds. Testing of these compounds embedded in polymethyl methacrylate (PMMA) revealed that their maximum emission peak wavelength occurs in the near-ultraviolet region, emitting short-wavelength light. However, the compounds disclosed in the aforementioned prior art all have a six-membered boron-oxygen ring structure, which has a relatively rigid planar surface and is prone to close packing between molecules, resulting in reduced luminous efficiency.

[0006] Therefore, in order to meet people's higher requirements for OLED devices, the field urgently needs to develop higher performance light-emitting materials containing boron-oxygen structures. Summary of the Invention

[0007] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a seven-membered ring boron-oxygen compound and its preparation method and electroluminescent device, so as to solve the technical problem of low luminous efficiency of existing boron-oxygen structure compounds as luminescent materials.

[0008] The present invention is achieved through the following technical solutions:

[0009] The first aspect of the present invention provides a seven-membered ring boron oxide compound, the structural formula of the seven-membered ring boron oxide compound is shown in formula (1):

[0010]

[0011] in:

[0012] R1 to R5 are each independently selected from H, F, cyano, trifluoromethyl, C1 to C 10 Alkyl and C2~C 10 Alkenyl, R1 to R5 are independent of each other or bonded;

[0013] R6~R9 are each independently selected from H, C1~C 10 Alkyl and C6~C 20 aromatic groups;

[0014] R 10 ~R 15 Each independently selected from H, D, hydroxyl, thiol, substituted or unsubstituted C2~C 10 Alkenyl, C6~C 20 Heteroaryl and substituted or unsubstituted C6~C 20 The aryl group, R 10 ~R 15 Independent of each other or bonded to each other;

[0015] X1 and X2 are each independently selected from C and N.

[0016] As used herein, the term "aryl" refers to an all-carbon monocyclic or fused polycyclic (ie, rings that share adjacent pairs of carbon atoms) group having a conjugated π electron system.

[0017] In the present invention, the term "bonded to each other" means that the group formed by the bond between two adjacent substituents can further bond to another nearby substituent.

[0018] The substituted or unsubstituted C6~C 20 The aryl group refers to C6~C 20 The aryl group may be substituted or not substituted by a substituent. 20 When the aryl group is substituted by a substituent, the substituent is D.

[0019] The substituted or unsubstituted C2~C 10 The alkenyl group refers to C2~C 10 The alkenyl group may be substituted or not substituted by a substituent. 10 When the alkenyl group is substituted by a substituent, the substituent is D.

[0020] Preferably, in the seven-membered ring boron oxide compound provided by the present invention, R6 to R9 are each independently selected from H, tert-butyl, phenyl and naphthyl, and R6 to R9 are not H at the same time.

[0021] Preferably, in the seven-membered ring borooxy compound provided by the present invention, R1, R3 and R5 are methyl groups, and R2 and R4 are H; or, R1, R3 and R5 are isopropyl groups, and R2 and R4 are H; or, R1, R2, R4 and R5 are all vinyl groups, R1 and R2 are bonded to form a phenyl group, R4 and R5 are bonded to form a phenyl group, and R3 is H.

[0022] Preferably, the seven-membered ring boron oxide compound provided by the present invention is one of the following compounds 1 to 112:

[0023] .

[0024] The second aspect of the present invention provides a method for preparing the seven-membered ring boron oxide compound, comprising the following steps:

[0025]

[0026] S1, compound a and compound b undergo Suzuki reaction to obtain intermediate Mn-1;

[0027] S2, the intermediate Mn-1 is subjected to a ring-closure reaction with BCl3, and then subjected to a coupling reaction with compound c to generate a seven-membered ring boron oxide compound as shown in formula (1).

[0028] Preferably, S1 in the preparation method of the seven-membered ring boron oxide compound is specifically: using a mixture of tetrahydrofuran (THF) and H2O as a solvent, K2CO3 as a base, and tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) as a catalyst, compound a and compound b are subjected to a Suzuki reaction to obtain the intermediate Mn-1.

[0029] Preferably, in the preparation method of the seven-membered ring boryl oxide compound, step S2 is specifically as follows: using a mixture of toluene and n-hexane as a solvent, under the catalysis of AlCl3, the intermediate Mn-1 is subjected to a ring-closing reaction with BCl3, and then subjected to a coupling reaction with compound c to generate a seven-membered ring boryl oxide compound as shown in formula (1).

[0030] The third aspect of the present invention provides an electroluminescent device, which includes an anode layer, a cathode layer, and an organic layer located between the anode layer and the cathode layer, the organic layer includes a hole transport layer, a light-emitting layer, and an electron transport layer, the hole transport layer is located between the anode layer and the light-emitting layer, the electron transport layer is located between the cathode layer and the light-emitting layer, the components of the light-emitting layer include a host light-emitting material and a guest light-emitting material, and the guest light-emitting material is the seven-membered ring boron oxide compound described in the present invention.

[0031] Preferably, the host luminescent material of the present invention includes a first host luminescent material and a second host luminescent material; wherein the first host luminescent material is selected from and , the second host luminescent material is selected from 、 、 and The mass ratio of the first host luminescent material to the second host luminescent material is 30:70~60:40.

[0032] Preferably, the mass fraction of the guest luminescent material in the present invention accounts for 0.1% to 3.0% of the mass fraction of the entire luminescent layer.

[0033] In a specific embodiment of the present invention, the organic electroluminescent device includes, from the anode layer to the cathode layer, a substrate, an anode layer, a hole injection layer (HIL), a hole transport layer, an electron blocking layer (EBL), an emission material layer (EML), a hole blocking layer (HBL), an electron transport layer, an electron injection layer (EIL), a cathode layer and a high refractive index covering layer (CPL).

[0034] The substrate needs to have high mechanical strength, excellent thermal stability, excellent water resistance, and excellent transparency; polyethylene terephthalate (PET) plastic is preferred.

[0035] In general, the anode layer material is preferably one with a high work function to facilitate hole injection into the organic layer. Specific examples of anode layer materials that can be used in the present invention include metals such as vanadium, chromium, copper, zinc, and gold, or alloys thereof; oxides such as zinc oxide, aluminum oxide, and tin dioxide; and conductive polymers such as polypyrrole and polyaniline.

[0036] The compounds used in the organic layers other than the light-emitting layer of the present invention can be small organic molecules, macroorganic molecules, polymers, and combinations thereof. The materials used for the hole injection layer, hole transport layer, electron blocking layer, hole blocking layer, electron transport layer, and electron injection layer are selected from industry-leading cost-effective materials. The compatibility of the various layers is determined through a series of tests and screening processes.

[0037] Preferably, the material of the hole injection layer in the present invention is MoO3.

[0038] Preferably, the material of the hole transport layer in the present invention is selected from one of the following materials:

[0039]

[0040] .

[0041] Preferably, the material of the electron blocking layer in the present invention is selected from one of the following materials:

[0042] .

[0043] Preferably, the material of the hole blocking layer in the present invention is selected from one of the following materials:

[0044] .

[0045] Preferably, the material of the electron transport layer in the present invention is selected from one of the following materials:

[0046] .

[0047] Preferably, the material of the electron injection layer in the present invention is LiF.

[0048] In order to facilitate electron injection into the functional organic layer, the cathode layer material is preferably a material with a low work function. Specific examples of cathode layer materials that can be used in the present invention include metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead, or alloys thereof, such as Mg-Al and Mg-Ag.

[0049] As a high refractive index covering layer, it can improve the refractive index of the cathode layer surface and increase the light extraction rate; the material of the covering layer is preferably .

[0050] A fourth aspect of the present invention provides a method for preparing the above-mentioned electroluminescent device, comprising adhering an anode layer to a substrate that has been pretreated and cleaned, and then sequentially vapor-depositing a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer of set thicknesses under low temperature conditions, and continuing to sputter-deposit a cathode layer and a high-refractive-index covering layer under low temperature conditions, and finally encapsulating the device using conventional device packaging methods to produce an electroluminescent device.

[0051] According to a fifth aspect of the present invention, a display panel is provided, wherein the display panel comprises the electroluminescent device according to the present invention.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The compound provided by the present invention contains a seven-membered borane structure. First, due to its certain flexibility, the seven-membered borane structure can better regulate the frontier orbital distribution of the molecule compared to the extremely rigid six-membered borane structure, so that the molecule has a more suitable energy level structure, which is conducive to the injection and transmission of electrons and holes, thereby improving the luminescence efficiency; secondly, the seven-membered borane structure can effectively inhibit the close π-π stacking interaction between molecules, reduce the fluorescence quenching phenomenon caused by aggregation, and maintain a high photoluminescence quantum yield (PLQY) in the aggregated state, thereby improving the performance of the electroluminescent device; thirdly, due to the valence electron difference effect between the B atom and the O atom, the seven-membered borane structure can achieve the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LOMO). Finally, the seven-membered ring boron-oxygen structure has a strong electron-withdrawing effect, which makes the frontier orbital overlap between the electron donor connected to it smaller, and realizes a small energy level difference between the S1 state and the T1 state, thereby realizing reverse intersystem crossing under thermal stimulation conditions and promoting luminescence.

[0054] Furthermore, in the seven-membered ring boron oxide compound provided by the present invention, R1, R3 and R5 are methyl groups, and R2 and R4 are H; or, R1, R3 and R5 are isopropyl groups, and R2 and R4 are H; or, R1, R2, R4 and R5 are all vinyl groups, R1 and R2 are bonded to form a phenyl group, R4 and R5 are bonded to form a phenyl group, and R3 is H; that is, the substituent connected to the B atom is 2,4,6-trimethylbenzene, 2,4,6-triisopropylbenzene or 9-position anthracene. These bulky substituents enhance the rigidity of the molecule, effectively protect the B atom, and improve the stability of the compound. At the same time, this rigid structure can reduce the probability of excited state energy being dissipated through non-radiative means such as thermal motion, so that more energy is released in the form of radiative transitions such as fluorescence / phosphorescence, thereby improving the luminous efficiency.

[0055] The raw materials of the seven-membered ring boryl oxide compound of the present invention are simple and easily available, the preparation method is simple, the reaction route is short, the post-treatment is simple, the yield is high, and the large-scale production of the seven-membered ring boryl oxide compound can be easily achieved.

[0056] The electroluminescent device provided by the present invention adopts the seven-membered ring boron oxide compound as the guest luminescent material in its luminescent layer, thereby effectively improving the luminous efficiency and extending the service life. In addition, the emission wavelength of the electroluminescent device is within the blue light range. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 is a cross-sectional view of the electroluminescent device of the present invention;

[0059] Figure 2 is the nuclear magnetic spectrum of compound 1 of the present invention;

[0060] Figure 3 is the NMR spectrum of compound 49 of the present invention;

[0061] Figure 4 is the NMR spectrum of compound 97 of the present invention. DETAILED DESCRIPTION

[0062] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content of the present invention description, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the present invention.

[0063] The following examples utilize conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the manufacturer's recommendations. Process equipment or devices not specifically specified in the following examples are conventional equipment or devices in the art. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art.

[0064] The important starting materials involved in the present invention include:

[0065] .

[0066] Compound Preparation Example 1 (Synthesis of Compound 1)

[0067]

[0068] Step 1:

[0069] Operation procedure: Under nitrogen protection, compound a1 (28.3 g, 0.1 mol), 160 mL of THF, 40 mL of water, compound b1 (19.4 g, 0.1 mol), Pd(PPh3)4 (2.3 g, 2 mmol), and K2CO3 (27.6 g, 0.2 mol) were added to a 500 mL three-necked flask. Stirring was started, and the system was heated to 110°C for 6 h. After the reaction, the system was cooled to room temperature, extracted with water and dichloromethane, and the organic phase was washed with saturated sodium chloride aqueous solution, dried, and concentrated. The residue was purified by silica gel column chromatography (petroleum ether: dichloromethane = 3:1) to obtain compound 1-1, weighing 26.8 g, with a yield of 76%, an HPLC (high performance liquid chromatography) content of 98%, and a molecular weight of 353.2 as determined by LC-MS.

[0070] Step 2:

[0071] Operation process: Under nitrogen protection, compound 1-1 (17.6g, 0.05mol), toluene (80mL) and n-hexane (80mL) were added to a 1000mL three-necked flask in sequence. Stirring was started, and boron trichloride (17.6g, 0.15mol) was slowly added dropwise. After stirring at room temperature for 40 hours, aluminum trichloride (0.3g, 2mmol) was quickly added. Then the reaction system was heated to 75°C and reacted for 8 hours. After the reaction was completed, the system was cooled to room temperature and compound c1 2,4,6-triisopropylphenylmagnesium bromide (0.15mol) was added dropwise. The reaction was continued with stirring for 1 hour. After the reaction was completed, the reaction solution was concentrated and the crude product was purified by silica gel column chromatography (petroleum ether: dichloromethane = 3:1) to obtain compound 1, weighing 21.2g, with a yield of 75%, an HPLC content of 99%, and a molecular weight of 565.4 shown by LC-MS. The nuclear magnetic spectrum of compound 1 is shown as follows Figure 2 shown.

[0072] H-NMR spectrum data of compound 1: 1 H-NMR (500 MHz, CD3OD) δ 8.98 (s, 1H), 7.76 (d, J = 15.0 Hz, 3H), 7.50 – 7.35 (m, 4H), 7.32 (s, 2H), 7.26 (s, 1H), 7.03 (s,2H), 6.88 (s, 1H), 2.87 (s, 3H), 1.43 (s, 9H), 1.18 (d, J = 15.0 Hz, 18H).

[0073] Compound Preparation Example 2 (Synthesis of Compound 49)

[0074]

[0075] Step 1:

[0076] Operation process: Referring to the synthesis process of compound a1 to compound 1-1, compound a6 (38.3 g, 0.1 mol) was used to replace compound a1 (28.3 g, 0.1 mol) to obtain compound 49-1, weighing 33.9 g, with a yield of 75%, HPLC content of 98%, and LC-MS showing a molecular weight of 453.2.

[0077] Step 2:

[0078] Operation process: Referring to the synthesis process of compound 1-1 to compound 1, compound 49-1 (22.6g, 0.05mol) was used to replace compound 1-1 (17.6g, 0.05mol), and compound c7 3,5-di-tert-butylmagnesium bromide (0.15mol) was used to replace 2,4,6-triisopropylphenylmagnesium bromide (0.15mol) to obtain compound 49, weighing 24.4g, with a yield of 75%, an HPLC content of 98%, and a molecular weight of 651.4 shown by LC-MS. The NMR spectrum of compound 49 is shown as follows Figure 3 shown.

[0079] H NMR spectrum data of compound 49: 1 H NMR (500 MHz, Chloroform) δ 8.95 (s, 1H),8.50 (s, 1H), 8.22 (d, J = 35.0 Hz, 3H), 7.80 (dd, J = 35.0, 30.0 Hz, 4H), 7.51 –7.28 (m, 7H), 6.89 (s, 1H), 1.43 (s, 9H), 1.32 (s, 18H).

[0080] Compound Preparation Example 3 (Synthesis of Compound 97)

[0081]

[0082] Step 1:

[0083] Operation process: refer to the synthesis process of compound a1 to compound 1-1, using compound a 14(20.8 g, 0.1 mol) replaced compound a1 (28.3 g, 0.1 mol) to obtain compound 97-1, weighing 22.6 g, with a yield of 76%, an HPLC content of 98%, and a molecular weight of 297.2 according to LC-MS.

[0084] Step 2:

[0085] Operation process: Referring to the synthesis process of compound 1-1 to compound 1, compound 97-1 (14.9 g, 0.05 mol) was used to replace compound 1-1 (17.6 g, 0.05 mol) to obtain compound 97, weighing 19.4 g, with a yield of 76%, HPLC content of 98%, and LC-MS showing a molecular weight of 510.3. The NMR spectrum of compound 97 is shown as follows Figure 4 shown.

[0086] H NMR spectrum data of compound 97: 1 H NMR (500 MHz, Chloroform) δ 8.84 (s, 1H), 8.48 (s, 1H), 7.78 (d, J = 30.0 Hz, 3H), 7.67 – 7.36 (m, 6H), 7.16 (s, 1H), 7.04 (s, 2H), 2.87 (s, 3H), 1.19 (d, J = 15.0 Hz, 18H).

[0087] The synthesis of other compounds refers to the synthesis process of compound 1, compound 49, and compound 97. During the synthesis, the corresponding starting materials compound a (a1~a 16 )、compound b(b1~b3)、compound c(c1~c 12 ).

[0088] The starting materials, LC-MS[M+1] and elemental analysis data of some compounds are shown in Table 1.

[0089]

[0090] According to the composition information of the light-emitting layer of the electroluminescent device given in Table 2, the electroluminescent devices of Examples 1 to 16 and Comparative Examples 1 to 3 were prepared.

[0091] The structural schematic diagrams of the electroluminescent devices in the embodiments and comparative examples of the present invention are shown in FIG. Figure 1 As shown, it includes a substrate 1, an anode layer 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9, a cathode layer 10 and a covering layer 11.

[0092]

[0093] Example 1 (Electroluminescent device containing compound 2)

[0094] An electroluminescent device containing compound 2, which comprises polyethylene terephthalate (PET) plastic, indium tin oxide (ITO) material, MoO3, HT-1, EB-1, light-emitting layer, HB-1, ET-1, LiF, Al-Mg (Al:Mg=9:1) and CPL in the order from the anode layer to the cathode layer; the material used in the CPL is ;

[0095] In the light-emitting layer, CBP and BCP are used as host light-emitting materials, and compound 2 is used as the guest light-emitting material, and the mass ratio of the three is 49:49:2.

[0096] The method for preparing the electroluminescent device containing compound 2 comprises the following steps:

[0097] 1. Use 1.5mm PET plastic as substrate 1 and 0.15mm ITO material as anode layer 2. Use alkaline washing, pure water washing, drying, and then ultraviolet-ozone washing to remove organic residues on the surface of PET plastic and ITO material.

[0098] 2. A layer of ITO material was adhered to PET plastic. Using a vacuum evaporation device, 20 nm thick MoO3 was evaporated as a hole injection layer 3. Then, 45 nm thick HT-1 was evaporated as a hole transport layer 4. Subsequently, 30 nm thick EB-1 was evaporated as an electron blocking layer 5. A 60 nm thick light-emitting layer 6 consisting of CBP, BCP, and compound 2 in a mass ratio of 49:49:2 was continuously evaporated on EB-1. Then, 10 nm thick HB-1 was evaporated on the light-emitting layer 6 as a hole blocking layer 7. Then, 30 nm thick ET-1 was evaporated as an electron transport layer 8. Finally, 16 nm thick LiF was evaporated on the electron transport layer 8 as an electron injection layer 9. After the electron injection layer 9 was evaporated, a 10 nm thick Al-Mg (Al:Mg=9:1) alloy was sputtered as a cathode layer 10 by low-temperature sputtering. Finally, 40 nm thick CPL was evaporated on the cathode layer 10 as a high refractive index covering layer 11.

[0099] 3. MoO3, HT-1, EB-1, light-emitting layer 6, HB-1, ET-1 and LiF layer are vacuum-encapsulated to prepare an electroluminescent device.

[0100] Examples 2 to 18

[0101] The difference from Example 1 is that Examples 2 to 18 respectively select compounds 14, 22, 23, 38, 46, 53, 63, 64, 79, 88, 92, 96, 99, 102, 104, 107 and 108 as the guest luminescent materials of the luminescent layer 6.

[0102] Comparative Example 1

[0103] The difference from Example 1 is that the light emitting layer 6 uses the Korean patent application with publication number KR1020090008736A. as guest luminescent materials.

[0104] The structure of the electroluminescent device is: PET substrate / ITO / MoO3 (20nm) / HT-1 (45nm) / EB-1 (30nm) / CBP:BCP: chemical formula 56=49:49:2 (60nm) / HB-1 (10nm) / ET-1 (30nm) / LiF (16nm) / Al:Mg=9:1 (10nm) / CPL (40nm).

[0105] Comparative Example 2

[0106] The difference from Example 1 is that the light emitting layer 6 uses the Korean patent application with publication number KR1020090008736A. as guest luminescent materials.

[0107] The structure of the electroluminescent device is: PET substrate / ITO / MoO3 (20nm) / HT-1 (45nm) / EB-1 (30nm) / CBP:BCP: chemical formula 59=49:49:2 (60nm) / HB-1 (10nm) / ET-2 (30nm) / LiF (16nm) / Al:Mg=9:1 (10nm) / CPL (40nm).

[0108] Comparative Example 3

[0109] The difference from Example 1 is that the light emitting layer 6 uses the Korean patent application with publication number KR1020090008736A. as guest luminescent materials.

[0110] The structure of the electroluminescent device is: PET substrate / ITO / MoO3 (20nm) / HT-1 (45nm) / EB-1 (30nm) / CBP:BCP: chemical formula 65=49:49:2 (60nm) / HB-1 (10nm) / ET-1 (30nm) / LiF (16nm) / Al:Mg=9:1 (10nm) / CPL (40nm).

[0111] The electroluminescent devices in the above examples and comparative examples were fabricated into 30 mm x 30 mm samples. Under the same device fabrication conditions, the anode and cathode layers were connected using a known driving circuit. The luminous performance of each electroluminescent device was then tested. For the electroluminescent devices, the driving voltage and luminous efficiency were measured at a current density of 10 mA / cm². The time required for the luminance to reach 95% of its initial luminance (LT) was measured at a current density of 20 mA / cm². 95 , i.e. lifespan). The test results are shown in Table 3.

[0112]

[0113] The performance data in Table 3 demonstrate that, compared to the electroluminescent devices prepared using the guest luminescent materials of Chemical Formula 56 and Chemical Formula 59 in the comparative examples (Comparative Examples 1-2), the electroluminescent devices prepared using the seven-membered ring boryl compound of the present invention as the guest luminescent material exhibit significantly improved overall luminous efficacy, with current efficiency increased by approximately 3 times and service life extended by more than 2 times. The performance data in Table 3 also demonstrate that, compared to the electroluminescent device prepared using the guest luminescent material of Chemical Formula 65 in the comparative example (Comparative Example 3), the electroluminescent devices prepared using the seven-membered ring boryl compound of the present invention as the guest luminescent material exhibit significant advantages in overall luminous efficacy, with current efficiency increased by nearly 100% and service life extended by 1.5 times. It can also be seen from the performance data in Table 3 that the current efficiency of the electroluminescent devices in Examples 1, 4, 7 to 9, and 13 to 15 is high and the color coordinates are significantly blue-shifted. This may be because the substituents connected to the B atoms in Compounds 2, 23, 53, 63, 64, 96, 99, and 102 corresponding to the above examples are 2,4,6-trimethylbenzene, 2,4,6-triisopropylbenzene, and 9-position anthracene, respectively. These bulky substituents enhance the rigidity of the molecule, effectively protect the B atom, and improve the stability of the compound. At the same time, this rigid structure can reduce the probability of excited state energy dissipation through non-radiative means such as thermal motion, allowing more energy to be released in the form of radiative transitions such as fluorescence / phosphorescence, thereby improving the luminous efficiency.

[0114] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A seven-membered ring boron-oxygen compound, characterized in that: The structural formula of the seven-membered ring boron oxide compound is shown in formula (1): in: R1 to R5 are each independently selected from H, F, cyano, trifluoromethyl, C1 to C 10 Alkyl and C2~C 10 Alkenyl, R1 to R5 are independent of each other or bonded; R6~R9 are each independently selected from H, C1~C 10 Alkyl and C6~C 20 aromatic groups; R 10 ~R 15 Each independently selected from H, D, hydroxyl, thiol, substituted or unsubstituted C2~C 10 Alkenyl, C6~C 20 Heteroaryl and substituted or unsubstituted C6~C 20 The aryl group, R 10 ~R 15 They are independent of each other or bonded to each other; when C2~C 10 When the alkenyl group is substituted by a substituent, the substituent is D; when C6~C 20 When the aryl group of is substituted by a substituent, the substituent is D; X1 and X2 are each independently selected from C and N.

2. The seven-membered ring boron-oxygen compound according to claim 1, characterized in that: R6 to R9 are each independently selected from H, tert-butyl, phenyl and naphthyl, and R6 to R9 are not H at the same time.

3. The seven-membered ring boron-oxygen compound according to claim 1, characterized in that: R1, R3 and R5 are methyl groups, R2 and R4 are H; or, R1, R3 and R5 are isopropyl groups, R2 and R4 are H; or, R1, R2, R4 and R5 are all vinyl groups, R1 and R2 are bonded to form a phenyl group, R4 and R5 are bonded to form a phenyl group, and R3 is H.

4. The seven-membered ring boron-oxygen compound according to claim 1, characterized in that: The seven-membered ring boron oxide compound is one of the following compounds 1 to 112: 。 5. The method for preparing the seven-membered ring boron oxide compound according to any one of claims 1 to 4, wherein: include: S1, compound a and compound b undergo Suzuki reaction to obtain intermediate Mn-1; S2, performing a ring-closing reaction on the intermediate Mn-1 and BCl3, and then performing a coupling reaction with compound c to obtain the seven-membered ring boron oxide compound; The structural formulas of compound a, compound b, intermediate Mn-1 and compound c are as follows: 。 6. The method for preparing a seven-membered ring boron-oxygen compound according to claim 5, wherein: S1 specifically comprises: using a mixture of tetrahydrofuran and H2O as a solvent, K2CO3 as a base, and tetrakis(triphenylphosphine)palladium as a catalyst, subjecting compound a and compound b to a Suzuki reaction to obtain an intermediate Mn-1.

7. The method for preparing a seven-membered ring boron-oxygen compound according to claim 5, wherein: S2 specifically comprises: using a mixture of toluene and n-hexane as a solvent, reacting the intermediate Mn-1 with BCl3 under the catalysis of AlCl3 to undergo a ring-closure reaction, and then performing a coupling reaction with compound c to obtain the seven-membered ring boron oxide compound.

8. An electroluminescent device, characterized in that The invention comprises an anode layer, a cathode layer and an organic layer located between the anode layer and the cathode layer, wherein the organic layer comprises a hole transport layer, a light-emitting layer and an electron transport layer, wherein the hole transport layer is located between the anode layer and the light-emitting layer, and the electron transport layer is located between the cathode layer and the light-emitting layer, and the components of the light-emitting layer include a host light-emitting material and a guest light-emitting material, wherein the guest light-emitting material is the seven-membered ring boron-oxygen compound according to any one of claims 1 to 4.

9. The electroluminescent device according to claim 8, characterized in that The host luminescent material includes a first host luminescent material and a second host luminescent material, wherein the first host luminescent material is selected from and , the second host luminescent material is selected from 、 、 and .

10. The electroluminescent device according to claim 8, characterized in that The material of the hole transport layer is selected from one of the following materials: The material of the electron transport layer is selected from one of the following materials: 。

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